CmdID

CmdID / Rules / Windows

Use of FSharp Interpreters

A Sigma rule for process creation on Windows, by Christopher Peacock @SecurePeacock, SCYTHE @scythe_io.

medium 1 ATT&CK technique 2 programs it names

What it looks for

its detection, as SigmaHQ writes it
detection:
  selection:
    - Image|endswith:
        - '\fsi.exe'
        - '\fsianycpu.exe'
    - OriginalFileName:
        - 'fsi.exe'
        - 'fsianycpu.exe'
  condition: selection

The rule’s detection, its selections and fields in order of name. The whole rule, with its references and false positives, is on SigmaHQ, by Christopher Peacock @SecurePeacock, SCYTHE @scythe_io, under the Detection Rule License 1.1. CmdID evaluates it on a command line alone: a test on what a command line cannot show, such as the parent process or the user, is not met.

Command lines that trip it

documented abuse, read by CmdID

The commands documented for fsi.exe, fsianycpu.exe trip it: each is on its program’s page, read by CmdID.

Programs and files it names

their pages here
fsi.exefsianycpu.exe

ATT&CK

the techniques it is tagged with
T1059Command and Scripting Interpreter

Other rules for T1059 Command and Scripting Interpreter

Suspicious Invocation of Shell via AWK - Linux · Capsh Shell Invocation - Linux · Atlassian Confluence CVE-2022-26134 · CVE-2023-22518 Exploitation Attempt - Suspicious Confluence Child Process (Linux) · Linux Suspicious Child Process from Node.js - React2Shell · Shell Execution via Git - Linux · Shai-Hulud Malware Indicators - Linux · Potential Netcat Reverse Shell Execution · Python Spawning Pretty TTY Via PTY Module · Inline Python Execution - Spawn Shell Via OS System Library · Shell Execution via Rsync - Linux · Suspicious Invocation of Shell via Rsync